Oops !That diagram appears to relate to the rare helium-3.
it's difficult to find a chart that goes above ~10K. Thanks....
okay, Thanks. It's becoming clearer to me.Oxygen has a melting point of 55 K and atmospheric pressure, slowly increasing with pressure. You don't want the oxygen to get colder than that, and you cannot fill in oxygen colder than 55 K.
What Elon said was the temperature was just above freezing and was -340°F or -207°C.
(reply #30 at https://forum.nasaspaceflight.com/index.php?PHPSESSID=pht92iam9tpu1iocsng4l1ak41&topic=39072.20 )
-207 is 66K ?
Boiling point is 90K
warming an ideal gas from 66 to 90 should raise its pressure by 90/66 = 1.36
i dont know yet how close is helium in those tanks to ideal